/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hbase.util;

import java.io.PrintStream;
import java.io.PrintWriter;

import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.hbase.Version;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class finds the Version information for HBase.
 */
@InterfaceAudience.Public
public class VersionInfo {
    private static final Logger LOG = LoggerFactory.getLogger(VersionInfo.class.getName());

    // If between two dots there is not a number, we regard it as a very large number so it is
    // higher than any numbers in the version.
    private static final int VERY_LARGE_NUMBER = 100000;

    /**
     * Get the hbase version.
     *
     * @return the hbase version string, eg. "0.6.3-dev"
     */
    public static String getVersion() {
        return Version.version;
    }

    /**
     * Get the subversion revision number for the root directory
     *
     * @return the revision number, eg. "451451"
     */
    public static String getRevision() {
        return Version.revision;
    }

    /**
     * The date that hbase was compiled.
     *
     * @return the compilation date in unix date format
     */
    public static String getDate() {
        return Version.date;
    }

    /**
     * The user that compiled hbase.
     *
     * @return the username of the user
     */
    public static String getUser() {
        return Version.user;
    }

    /**
     * Get the subversion URL for the root hbase directory.
     *
     * @return the url
     */
    public static String getUrl() {
        return Version.url;
    }

    static String[] versionReport() {
        return new String[]{"HBase " + getVersion(), "Source code repository " + getUrl() + " revision=" + getRevision(), "Compiled by " + getUser() + " on " + getDate(), "From source with checksum " + getSrcChecksum()};
    }

    /**
     * Get the checksum of the source files from which Hadoop was compiled.
     *
     * @return a string that uniquely identifies the source
     **/
    public static String getSrcChecksum() {
        return Version.srcChecksum;
    }

    public static void writeTo(PrintWriter out) {
        for(String line : versionReport()) {
            out.println(line);
        }
    }

    public static void writeTo(PrintStream out) {
        for(String line : versionReport()) {
            out.println(line);
        }
    }

    public static void logVersion() {
        for(String line : versionReport()) {
            LOG.info(line);
        }
    }

    public static int compareVersion(String v1, String v2) {
        //fast compare equals first
        if(v1.equals(v2)) {
            return 0;
        }
        String[] v1Comps = getVersionComponents(v1);
        String[] v2Comps = getVersionComponents(v2);

        int length = Math.max(v1Comps.length, v2Comps.length);
        for(int i = 0; i < length; i++) {
            Integer va = i < v1Comps.length ? Integer.parseInt(v1Comps[i]) : 0;
            Integer vb = i < v2Comps.length ? Integer.parseInt(v2Comps[i]) : 0;
            int compare = va.compareTo(vb);
            if(compare != 0) {
                return compare;
            }
        }
        return 0;
    }

    /**
     * Returns the version components as String objects
     * Examples: "1.2.3" returns ["1", "2", "3"], "4.5.6-SNAPSHOT" returns ["4", "5", "6", "-1"]
     * "4.5.6-beta" returns ["4", "5", "6", "-2"], "4.5.6-alpha" returns ["4", "5", "6", "-3"]
     * "4.5.6-UNKNOW" returns ["4", "5", "6", "-4"]
     *
     * @return the components of the version string
     */
    private static String[] getVersionComponents(final String version) {
        assert (version != null);
        String[] strComps = version.split("[\\.-]");
        assert (strComps.length > 0);

        String[] comps = new String[strComps.length];
        for(int i = 0; i < strComps.length; ++i) {
            if(StringUtils.isNumeric(strComps[i])) {
                comps[i] = strComps[i];
            } else if(StringUtils.isEmpty(strComps[i])) {
                comps[i] = String.valueOf(VERY_LARGE_NUMBER);
            } else {
                if("SNAPSHOT".equals(strComps[i])) {
                    comps[i] = "-1";
                } else if("beta".equals(strComps[i])) {
                    comps[i] = "-2";
                } else if("alpha".equals(strComps[i])) {
                    comps[i] = "-3";
                } else {
                    comps[i] = "-4";
                }
            }
        }
        return comps;
    }

    public static int getMajorVersion(String version) {
        return Integer.parseInt(version.split("\\.")[0]);
    }

    public static void main(String[] args) {
        writeTo(System.out);
    }
}
